Process for making cockled paper



P 13, 1966 G. J. PASEK ETAL 3,272,643

PROCESS FOR MAKING COCKLED PAPER Filed Aug. 2, 1962 5 Sheets-Sheet l pt. 13, 1966 G. J. PASEK ETAL 3,

PROCESS FOR MAKING COGKLED PAPER Filed Aug. 2, 1962 5 Sheets-Sheet 2 p 13, 1966 ca. J. PASEK ETAL 3,272,643

PROCESS FOR MAKING COCKLED PAPER Filed Aug. 2, 1962 5 Sheets-Sheet 3 United States Patent 3,272,643 PROCESS FOR MAKING COCKLED PAPER George I. Paselr, Neenah, and Karl E. Sager, Appleton, Wis., assignors to Kimberly-Clark Corporation, Neenah, Wis., a corporation of Delaware Filed Aug. 2, 1962, Ser. No. 214,237 4 Claims. (Cl. 11711) Our invention relates to the manufacture of paper and, more particularly, to a method and apparatus for producing a paper having a cockled finish.

Prior to our invention, cockled finished paper has generally been made off or separate from the papermaking machine. Previously manufactured smooth finished paper has been drawn from reels through a sizing bath, and the paper has then been air dried, such as by means of the well-known festoon drier which supports the paper in the form of loops between traveling spaced rods. The cockles in the paper, which are spots that are warped or bulged from the general plane of the sheet, are produced on account of excessive and uneven shrinkage during drying.

It is an object of the present invention to provide an improved method and apparatus for manufacturing cockled paper which is operative at considerably higher speeds than conventional apparatus so that the paper may be provided with this finish directly from the papermaking machine, without the necessity of first storing the paper in reel form.

It is also an object of the invention to provide improved papermaking apparatus which is usable alternately for the manufacture of cockled finish paper or which may be used to make smooth finished paper.

In brief, we have found, according to the invention, that cockled finished paper may be made at very high speeds if the paper is preliminarily and unevenly stretched after having sizing applied to it and before the paper is dried, and we have found that the preliminary uneven stretching of the paper successfully takes the place of considerable air drying, with the same fine cockled finish being obtained as with conventional apparatus.

The invention consists of the novel methods and constructions to be hereinafter described and claimed for carrying out the above stated objects, and such other ob jects, as will be apparent from the following description of a preferred mode of practicing the invention, illustrated with reference to the accompanying drawings, wherein:

FIG. 1 is a schematic side elevational view of paper cockling apparatus embodying the principles of the invention and including a pair of rolls having cockled external surfaces and including also an air float drier having top and bottom air plenums;

FIG. 2 is a side elevational view on an enlarged scale of the air float drier with the side wall being broken away to show internal construction;

FIG, 3 is a fragmentary plan view on an enlarged scale of the bottom plenum of the dried;

FIG. 4 is a sectional view on a still further enlarged scale taken on line 4-4 of FIG. 3;

FIG. 5 is a perspective view of one of the cockled surface rolls; and

FIG. 6 is a schematic side elevational view of an electrically operated drier which may be substituted for the air float drier illustrated in FIG. 1.

Like characters of reference designate like parts in the several views.

Referring to FIG. 1, the illustrated apparatus may be seen to comprise, in general, a size press 10, cockled surfaced cylinders 11 and 12, an air float drier 13, can driers 14 and 15, and a calender 16.

The size press 10 com-prises a pair of rolls 17 and 18, each of which preferably is of the type having a cover 19 of yieldable rubberlike material. The rolls 17 and 18 have a nip between them for containing a body 20 of sizing which is supplied into the nip from suitable conduits 21. The sizing 20 is made up with the usual constituents of sizing for paper, principally starch and water. The paper web A passes into the size press 10, and preferably a conventional mount hope roll 22 is provided just ahead of the size press 10 for spreading and smoothing the paper. The web A may be taken in dry condition directly from a conventional Fourdrinier papermaking machine for on-the-machine operation, or alternately, the web A may be taken from a paper supply roll (not shown) for offthe-machine operation.

The cylinders 11 and 12 are provided with cockled surfaces, that is, surfaces provided with rounded, randomly and irregularly shaped bosses 23 of random spacing and size which are raised from a cylindrical roll surface 24 (see FIG. 5 showing the roll 11). Although the bosses may vary drastically in height and size while still obtaining the advantages of the invention, we have found that the bosses 23 may well vary in height from .005 inch to .05 inch, and the largest transverse dimension or diameter of the bosses may well vary from /s inch to A2 inch. The rolls 11 and 12 are preferably hollow and are heated in any suitable manner, such as by the application of steam to them, preferably being maintained at to 300 degrees Fahrenheit surface temperature.

An endless felt 25 extends about a part of the periphery of the roll 11, the felt being held in the form of a loop by means of guide rolls 26, 27 and 28. A mount hope roll 29 is provided between the press 10 and the roll 11 so that the web A passes onto the surface of the roll 11 after passage over the mount hope roll, with the felt 25 being arranged to hold the web A in forceful contact with the surface of the roll 11.

p A roll 30 having a covering 31 of yieldable rubberlike material has a pressure nip with the cylinder 12, and the web A passes through this nip and is thus held in forceful contact with the cylinder 12.

A pair of guide rolls 32 and 33 are provided for the web A for guiding it subsequent to its passage over the cylinder 12. The web A passes between a pair of pull rolls 34 and 35 having a nip between them -at one end of the air float drier 13, and the roll 35 preferably has a yieldable rubberlike covering 36. A mount hope roll 37 is preferably provided between the roll 33 and the rolls 34 and 35.

The air float drier 13 comprises a top plenum 38 and a bottom plenum 39. The plenums are respectively provided with air return plates 40 and 41 which are substantially parallel and opposite to each other and are spaced about /2 inch to l-inch apart. Each of these plates is provided with a plurality of air exhaust openings 42 and an air inlet jet tube 43 is disposed within each of the openings 42. Each of the tubes 43 is centered in its respective opening 42 and terminates slightly short of the plate 40. The openings 42 may, for example, be about 1 /2 inch in diameter and the jet tubes 43 may, for example, have an internal diameter of about /3 inch.

The web A passes between the plenums 38 and 39, and the openings 43 are staggered in the direction of movement of the web indicated by the arrows B (see FIG. 3), the openings 42, for example, being disposed on threeinch triangular centers. Each opening 42 and each jet tube 43 in one of the plenums is disposed directly opposite a corresponding opening 42 and jet tube 43 in the opposite plenum.

Hot air at 300 degrees to 600 degrees Fahrenheit, for example, and at velocities of 2000 and 8000 feet per minute, for example, is supplied to the jet tubes 43. The construction of the return openings and jet tubes is such that with air being so supplied to the plenums 38 and 39, the air creates a controlled interference pattern and centers the web A between the opposed plenums 38 and 39. It is contemplated that this web supporting action of the plenums shall be sufficient in itself to maintain the web A traveling substantially midway between the surfaces 40 and 41 and that the web shall be under substantially no tension as it passes between the plenums.

A pair of tension control rolls 44 and 45 having a nip between them are provided at the discharge end of the drier 13, the roll 45 preferably having a yieldable rubberlike covering 46. A mount hope roll 47 is provided for the web A after passage of the web between the rolls 44 and 45, and the web may be wound on a suitable conventional reel (not shown) after passage over the mount hope roll 47.

The cockled surfaced cylinders 11 and 12, together with the air float drier 13, result in a high quality cockled surfaced paper as will be hereinafter described more in detail. If it is desired that the paper produced shall be of the smooth type rather than the cockled type, other equipment now to be specifically described may be utilized. The web A which is to be of the smooth type, in lieu of being passed over the rolls 29, 11, 12 and 32, instead is passed over a turning roll 48, as shown in dotted lines in FIG. 1. The web A then passes over the rolls 33, 37, 34, 35, 44 and 45 and through the drier 13 in the same manner as the cockled finished web A. Additional drying equipment comprising the can driers 14 and 15, which may be steam heated in accordance with conventional practice, is utilized for the smooth finished paper web A. An endless canvas 49 is provided for the drier 15, being supported by means of rolls 50, 51, 52 and 53 so that it extends partially around the drier 15. A similar endless canvas 54 is provided for the drier 14, the canvas 54 being supported by rolls 55, 56, 57 and 58. As will be observed from FIG. 1, the web A passes over the drier from the roll 44, and from thence over the drier 14, with the canvases 49 and 54 holding the web in tight contact with the driers 14 and 15.

The calendar 16 is intended for use with the web A and comprises a lowermost driving king roll 59 and smaller rolls 60, 61 and 62 disposed above and driven by the king roll. A stabilizer roll 63 is provided for receiving the web A 011 the drier 14, and the web A passes between the rolls 61 and 62 of the calendar 16 from the roll 63 and from thence around the rolls 60 and 61 and through the other roll nips of the calender, to be taken from the lowermost nip of the calender for conventional reeling into a roll. The uppermost small roll 62 of the calender 16 is so mounted as to be movable upwardly off the roll 61 so that the web A may pass directly between the rolls 61 and 62 to the reel without contacting either of these rolls.

In operation, for making cockled finished paper, the web A travels as shown in full lines in FIG. 1. The web A may be substantially dry in being drawn from an offmachine reel, or in being drawn directly from a papermaking machine, to the size press 10 and may, for example, have about six percent moisture content. Although the size press 10 may be arranged to cause the web A to pick up various amounts of sizing, a percent pickup is usual at which a pound of paper entering the size press emerges from the press to weigh 1.3 pounds. Eventually, most of this increased weight is lost; the Web after drying and cockling may, for example, be left with only a three percent increase in weight. The amount of sizing imparted to the web may be changed particularly by changing the pressure between the rolls 17 and 18. As has been mentioned, the sizing is of conventional chemical makeup, being principally starch and water, mostly the latter; and the water evaporates during the drying process to leave only the solids on the paper.

The web A passes over the rolls 11 and 12 and thus has the outlines of the bosses 23 impressed or embossed on it. In impressing the shapes of the lands 23 on the paper, the cylinders 11 and 12 are preferably heated, such as by the application of steam to the rolls in a conventional manner, the heating being to degrees to 300 degrees Fahrenheit, for example; and the cylinders 11 and 12 thus have a preliminary drying effect on the paper. The felt 25 and the roll 30 maintain the paper in close contact with the surfaces of the rolls 11 and 12 so as to accentuate and assure this embossing action. As will be understood, if desired, a roll 30 may be substituted for the felt 25 and a felt 25 may be substituted for the roll 30, since both the roll 30 and the felt 25 function in much the same manner to assure close contact of the web A with the respective cylinders 11 and 12. It will be understood also that an embossing roll may be substituted for the soft surfaced roll 30 for either of the cylinders 11 and 12, with the embossing roll having a cockled surface similar to that on the respective cylinder 11 or 12 but having a boss of the same size and shape as each surface depression in the cylinder 11 or 12 to thus have a surface meshing engagement with the respective cylinder 11 or 12.

The cylinders 11 and 12, particularly since the web A is relatively wet with sizing as it passes over the cylinders, thus cause a physical distortion of the web A by the cockled surfaces of these rolls to give the web an embossed cockled finish which corresponds in pattern with the surfaces of the cylinders 11 and 12. This preliminary cockling of the web A insures the subsequent development during drying and retention after drying of the cockled effect, and the cockled effect is accentuated, enhanced and made permanent due to the particular mode of drying the web that is provided by the air float drier 13, under zero web tension and with the web being supported only on air as it is being dried. The web A passes between the plenums 38 and 39 in the direction indicated by the arrow B in FIG. 3 and floats between the plenums, being supported solely by the air impinging on the web A from the jet tubes 43. The pull rolls 34 and 35 and the rolls 44 and 45, which act as tension control rolls, are so driven that the Web A is under substantially zero tension as it passes between the plenums 38 and 39, and there thus is no substantial tendency for the precockled finish on the paper to be drawn out of it. The mount hope rolls 29 and 37 prior to and subsequent to the cylinders 11 and 12 in the path of the web A function to maintain the paper web spread smooth in accordance with conventional operation of such rolls.

The web A, subsequent to drying by the drier 13, is passed over the mount hope roll 47 to be wound on the conventional reel.

Although we prefer the air float drier 13 for drying the web A and producing the accentuated cockled effect on the web, other drying devices in which the web A is under substantially zero tension may be used instead, such as an electrical radiant dn'er 64 shown in FIG. 6. The drier 64 comprises a. pair of opposite, closely spaced, panels 65 and 66, heated respectively by electric heater elements 67 and 68. Rolls 34a and 35a corresponding to the rolls 34 and 35 and rolls 44a and 45a corresponding to the rolls 44 and 45 are so driven that the sheet A is slack as it passes between the panels 65 and 66. The panels 65 and 66 apply radiant heat on the web A and dry it as it passes downwardly between the panels 65 and 66.

If it is desired to produce smooth finish paper, the path of the web is changed to that indicated by the web A. The web A passes through the press 10 substantially directly to the drier 13, exclusive of the cylinders 11 and 12. Sizing may or may not be used in the press 10, as desired; however, if no sizing is used, it is contemplated that the web shall not be completely dry as it passes to the drier l3.

The air float drier 13 is supplied with air at such temperatures and velocity to partially dry the web A, and drying of the web A is completed by the driers 14 and 15. The web A is held in tight contact with the driers 14 and 15, and since the peripheral surfaces of the driers '14 and 15 are smooth, the web A with a smooth finish results. The finish of the web A is made even smoother by the calender 16, in accordance with well-known principles of operation of paper calenders.

It will be understood that conventional driving mechanism can be utilized in connection with the various rolls and cylinders of the apparatus. The rolls 17 and 18 of the size press, the cylinders 11 and 12 and the driers 14 and 15 may, for example, be driven along with various others of the rolls. As has been mentioned, the rolls 34 and 35 and the rolls 44 and 45 are so driven that the web is slack as it passes between the plenums 38 and 39, and the Web A is also preferably maintained quite slack subsequent to passage from the cylinder 12 to the drier 13.

Heating of the driers 14 and 15 and of the cylinders 11 and 12 is accomplished by conventional heating devices. The cylinders 11 and 12 and driers 14 and 15 may, for example, be hollow and steam may be supplied to these cylinders.

We have found that by providing the preliminary cockling effect on the web by means of the cockled external surfaces of the cylinders 11 and 12, with the web being partially dried by these cylinders, a highly satisfactory cockled product is produced It is not necessary that the cylinders 11 and 12 be effective for long durations of time on the web A; the time of contact with the web by the cylinders may be less than a second. Under some conditions, only one of the cylinders 11 and 12 may be utilized; however, particularly for heavier grades of paper, we prefer the use of both cylinders 11 and 12. The desirable ultimate cockled finish of the product may be considered to be the effect of the initiation of the cockled effect by the simulated cockled surfaces on the cylinders 11 and 12, which physically distort the wet web to have a simulated cockled finish, followed by the completion of the drying of the web at a minimum tension as it passes through the drier 13. The drier 13 effective subsequently on the precokcled Web A has been found not only to retain the cockled effect previously produced by the cylinders 11 and 12 on the web, but to develop and increase the cockling, so that a fine quality end product is obtained. The above described apparatus, including the cylinders 11 and 12 and the air float drier 13, may be used to replace the conventional lofting operation, including the festoon drier, with resultant savings in space and capital cost, large reductions in operating costs and waste, and increased production. In this connection, it may be mentioned that a festoon drier commonly is operated at 150 to 200 feet per minute while the cockling apparatus described herein will operate satisfactorily between 400 and 1000 feet per minute, for example, while still producing a very satisfying cockled product.

Great savings may be had by the herein described apparatus, since it can be operated in tandem with an ordinary papermaking machine, permitting the production of either cockled or flat paper at will, and eliminating a separate cockling or lofting operation. The illustrated apparatus may be used in tandem with a papermaking machine, since its speed matches that of conventional papermaking machines effective at present for making bond grades for which the apparatus is particularly useful.

Due to the increased speed with which the web A passes through our apparatus, the penetration time of the sizing solution into the web is decreased as compared to time of penetration with conventional relatively slow cockling apparatus using a festoon drier. The physical distortion or precockling of the paper web A produced by the cylinders 11 and 12 has been found especially desirable to compensate for the reduced penetration time of the sizing solution, and the cylinders 11 and 12 permit the use of wider ranges of the constituents of sizing solution, wider ranges of viscosities of sizing solution, and a wider range of weights of base sheets. The precockling step results advantageously in the development of a satisfactory cockled finish after subsequent drying in spite of any web tensions which otherwise might tend to destroy the cockled finish.

Air velocities of 2000 to 8000 feet per minute from the jet tubes 43 of the drier 13 may be considered moderate and will not damage the web A which is unsupported in passing between the plenums 38 and 39. Since the Web is supported by the air jets from the plenums 38 and 39 rather than by other guides or rolls, a minimum tension of the web is maintained which is particularly desirable for cockling, even though the web passes horizontally through the drier 13. With the drier 13, the web A substantially as a slack sheet is floated between opposed cushions of hot air while still being dried at a high rate. It may be understood that if desired, the temperatures of the air from the two plenums 38 and 39 may be varied, particularly to control the cockling effect on the paper.

It will be understood that although minimum tension is maintained on the web A as it passes through the drier 13, the tension on the web may be increased subsequent to the rolls 44 and 45 for satisfactory reeling, since the web A is dry at this time.

Due to the fact that long loops of festooned paper are not required with the present apparatus, large amounts of paper are not wasted in threading and starting and stopping the apparatus as with conventional machines.

The tension on the web A for making flat finished paper is preferably higher than that on the web A for minimizing any cockling tendencies of the web, but unduly high tensions of the web A should be avoided. For flat finishing, it is contemplated that the air float drier 13 shall still carry the larger drying load, and the drier cylinders 14 and 15 shall finish the drying operation as well as insuring flatness due to the smooth external surfaces of the driers 14 and 15. It is contemplated that, under normal conditions, only two steam heated cylindrical driers 14 and 15 will be needed because of the high rates of drying obtainable by the air float drier 13. In this connection, it may be noted that the overall length of the drying section of the herein described machine for producing the flat finished paper, including the drier 13 and the two cylinders 14 and 15, is less than a conventional multi-cylinder drier section following a size press.

The herein described apparatus for initiating the cockle with positive physical distortion and for keeping the precockled web under minimum tension advantageously produces a controlled cockle size and intensity of cockling. At the same time, any appearance of having mechanically embossed the web is avoided, since final drying of the web is by the air float drier 13 independent of the heated cockle surfaced cylinders 11 and 12.

We wish it to be understood that the invention is not to be limited to the specific methods and constructions shown and described, except only insofar as the claims may be so limited, as it will be apparent to those skilled in the art that changes may be made without departing from the principles of the invention.

We claim:

1. In a method for making cockled paper, the steps which comprise, utilizing a dry paper web and passing it through a bath of liquid sizing, subsequently traveling the paper web as so wetted over a rotating cylinder which is heated to between F. and 300 F. surface temperature and holding the web forcefully in contact with the cylinder as it passes over the cylinder, said cylinder having an uneven external surface comprising a plurality of bosses which are of irregular spacing and size and shape and are between .005 inch to .05 inch in height and have diameters or largest transverse dimensions of inch to /2 inch so that the cylinder patterns the web in partially drying it, and subsequently completing the drying of the web while maintaining the web under a minimum tension.

2. In a method for making cockled paper, the steps which comprise, applying a moist paper Web in contact with a heated surface having a plurality of bosses of random spacing and size and of rounded, irregular and random shapes so as to partially dry the web, and subsequently completing the drying of the web while maintaining the web under a minimum tension.

3. In a method for making cockled paper, the steps which comprise, utilizing a dry paper web and passing it through a bath of liquid sizing, subsequently traveling the paper web as so wetted over a heated rotating cylinder and holding the web forcefully in contact with the cylinder as it passes over the cylinder, said cylinder having an uneven external surface comprising a plurality of bosses of random spacing and size and of rounded, irregular and random shapes so that the cylinder patterns the web in partially drying it, and subsequently completing the drying of the web while maintaining the web under a minimum tension.

4. In a method for making cockled paper, the steps which comprise, utilizing a dry paper web and passing it through a liquid bath so as to wet the web, subsequently traveling the paper web as so wetted over a rotating heated cylinder in contact with one surface of the Web and subsequently passing the paper web over a second rotating heated cylinder in contact with the other surface of the web, each of said cylinders having an uneven external surface comprising a plurality of bosses of random spacing and size and of rounded, irregular and random shapes so as to have an irregular partial drying effect on the web as it passes over the cylinder, and subsequently completing the drying of the web while maintaining the web under a minimum tension.

References Cited by the Examiner UNITED STATES PATENTS 1,686,388 10/1928 Lorenz 162-113 1,810,145 6/1931 Ross 117-11 1,819,793 8/1931 Ross 118-44 2,043,635 6/1936 Swift 118-44 2,216,803 10/1940 Benda 117-11 X 2,460,042 1/ 1949 Stafford 117-11 2,940,891 6/1960 Muller 162-113 3,104,197 9/1963 Back et a1 162-113 3,164,512 1/1965 Dixson et a1. 117-11 X FOREIGN PATENTS 389,143 6/ 1908 France.

ALFRED L. LEAVITT, Primary Examiner.

WILLIAM D. MARTIN, RICHARD D. NEVIUS,

Examiners.

R. S. KENDALL, J. P. MCINTOSH, Assistant Examiners. 

1. IN A METHOD FOR MAKING COCKLED PAPER, THE STEPS WHICH COMPRISES, APPLYING A MOIST PAPER WEB IN CONTACT WITH A HEATED SURFACE HAVING A PLURALITY OF BOSSES OF RANDOM SPACING AND SIZE AND OF ROUNDED, IRREGULAR AND RANDOM SHAPES SO AS TO PARTIALLY DRY THE WEB, AND SUBSEQUENTLY COMPLETING THE DRYING OF THE WEB WHILE MAINTAINING THE WEB UNDER A MINIMUM TENSION. 